Apparatus for defrosting refrigerators



Nov. 14, 1961 M. J. HILER 3,008,306

APPARATUS FOR DEFROSTING REFRIGERATORS Filed May 1. 1959 Fig.

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MALVER/V 1 H/LER A'ITORNEY5 INVENTOR United States Patent Ohio Filed May 1, 1959, Ser. No. 810,394 1 Claim. (Cl. 62-283) The present invention relates to the defrosting of household refrigerators, more particularly, to inducing the accumulation of frost upon a specific surface so as to prevent the frost from accumulating on the evaporator and thereby reducing its efliciency.

Household refrigerators comprise evaporators of the type which are adapted to operate at temperatures below the freezing point of Water. Evaporators of this type are generally located in the storage compartment so as to be readily contacted by moisture-laden air in the compartment. Thus, these cvaporators are susceptible to the rapid accumulation of frost thereon. The accumulation of frost upon the surfaces of the evaporator considerably decreases the efliciency of the evaporator as it operates in the storage compartment of the refrigerator. Thus, it is necessary to periodically remove the accumulation of frost in order that the refrigerator may function effectively. Such a defrosting, however, involves a substantial interruption in the refrigerant process and may result in the spoilage of foodstuffs which are stored therein. Furthermore, some of these defrosting processes re quire considerable time and labor in order to effectively remove the accumulations of frost.

In the present invention, the above disadvantages are overcome by providing a structure in the refrigerator upon which the accumulation of frost is induced. This structure is readily removable from the refrigerator, so that it is merely necessary to remove these surfaces from the refrigerator and remove the accumulations of frost therefrom, to refrost the refrigerator. This process can be accomplished without interrupting the refrigerating process. By providing a surface upon which the accumulation of frost is induced, frost is prevented from accumulating on the surfaces of the evaporator. Thus, this invention provides for the effective operation of the refrigerant evaporator, since there will be no accumulations of frost on the evaporator to impair the evaporating process.

In carrying out this invention, there is provided a supercold spot which becomes the focal point of the crystallization of ice which forms the frost. This build-up of the frost upon this supercold spot prevents the accumulation of frost upon the surfaces of the evaporator.

When the detachable surfaces forming the cold spot are removed from the refrigerator, the ice is readily melted off in a conventional manner, such as by submerging the frost-laden surface in hot water.

It is therefore the principal object of this invention to provide a novel and improved apparatus for the defrosting of a refrigerator.

It is another object of this invention to provide an apparatus for inducing the accumulation of frost on a surface Which is spaced from the evaporator. I

It is a further object of this invention to provide an apparatus for the rapid removal of the accumulation of frost on the cold surface of a refrigerator.

Other objects and advantages of this invention will become apparent upon reference to the accompanying description, when taken in conjunction with the following drawings. wherein:

FIGURE 1 is a fragmentary front elevational view of the storage compartment of a refrigerator incorporating the supercold surfaces of this invention;

FIGURE 2 is a sectional view taken along the line 22 of FIGURE 1 to show in elevation the detachable cold surface; and

FIGURE 3 is an over-all perspective view of the detachable cold surface removed from the refrigerator.

Proceeding next to the drawings, wherein like reference symbols indicate the same parts throughout the various views, in FIGURE 1 there is shown a refrigerator cabinet indicated at 1 and having a food-storage compartment 2 which is defined by the. cabinet wall structure 3. The cabinet wall structure comprises an outer shell and an inner liner which is filled with insulating material. While not shown, it is understood that the refrigerator would include a door which is hingedly mounted so as to seal against the forward face of the cabinet as shown in FIG URE 1. Shelves 4 are slidably mounted in the storage compartment in a conventional manner.

The entire storage compartment as described above is for the purpose of storing foodstuffs at temperatures above the freezing point of water. The relative humidity of the air in such a compartment will frequently reach high values.

Located within the storage compartment is a freezer compartment indicated generally at 5 and maintained at a temperature below the freezing point of water. The compartment 5 is similarly closed by a door which is not shown in the drawings. The freezer compartment 5 is formed from sheet material which has continuous passages therein so as to form an evaporator for the refrigerant. These passages usually define a continuous tortuous passage over the entire surface of the freezer compartment 5. It is upon this evaporator surface that the frost accumulates in a conventional refrigerator.

Mounted below the freezer compartment 5 is a drip tray 6 slidably supported on a rack 7.

In order to form a detachable supercold surface in the compartment of the refrigerator, an additional refrigerant evaporator located at 8 is mounted on the walls of the storage compartment adjacent the freezer compartment. The additional evaporator 8 comprises a tube formed into a shape comprising a series of reverse bends, and the tube is connected to the same source of refrigerant as the passages in the wall of the freezer compartment 5. This additional refrigerant evaporator may be mounted on either one or both sides of the freezer compartment. A detachable cover member 9 is positioned adjacent the evaporator 8, preferably to be in contact therewith. The cover member 9 is slidably retained between upper and lower slides lil and 11 and may be secured in position by latch means indicated at 12.

Portions 13 of the cover member 9, which correspond to the shape of the evaporator 8, are formed from a material which has a higher thermal conductivity than any of the other material used in the storage compartment. Such a material could be silver, but any other metallic or non-metallic material of a sufiiciently high thermal conductivity may be used. Since the thermal conductivity of the cold spot portions 13 is much greater than that of the material comprising the cover plate 9, it can be seen that the temperature of the portions 13 will be lower than that of either the cover member 9 or the walls of the evaporator forming the freezer compartment 5. This localized low-temperature cold spot will provide a nucleus for the accumulation of frost. Since conditions for the accumulation of frost will be much more favorable on the cold spot portions 13 than on the evaporator 5, very little, if any, frost will accumulate on the walls of the refrigerant evaporator.

The detachable cover member 9 has a flange 14 at one end thereof which positions the member properly with respect to the evaporator 8. A handle may be provided .011 the flange 14 to facilitate the removal and insertion of the cover member 9.

While the refrigerant in the evaporator 8, as illustrated in FIGURE 2, is maintained at the same temperature as' the refrigerant in the evaporator of the freezer compartment the structure may be modified by maintaining the refrigerant in the evaporator S at a lower temperature than that in the evaporator of the freezer compartment. The lower temperature of the evaporator 8, plus the high thermal conductivity of the cold spot portions 13, will provide favorable conditions for the accumulation of frost on portions of the cover member 9.

Thus, while the moisture-laden air of the storage compartment is in contact with the evaporator surface of the freezer compartment, the existence of the cold spot portions will result in the accumulation of frost upon these cold spot portions rather than upon the surface of the evaporator.

While the detachable member and additional evapora tor 8 have been positioned in the storage compartment at the level of the freezer compartment, it is to be understood that other locations in the storage compartment would also be satisfactory. Localized cold spot areas may be formed either above or below the freezer compartment, or may even be formed in the walls of the freezer compartment itself.

' Thus it can be seen that the present invention provides a a specific surface which acts as the focal point for the accumulation of frost in the refrigerator. Since this surface is readily removable from the refrigerator, accumula t-ions of ice can be easily removed therefrom. Further,

d the accumulations of ice on these cold spot areas will tend to prevent the accumulation of frost on the refrigerant evaporators. This elimination of frost on the evaporators will provide a refrigerator which will operate at a higher efficiency than when the evaporator surfaces are coated with accumulations of frost.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and, accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claim.

What I claim is:

In a refrigerator, a storage compartment, a first refrigerant evaporator in said storage compartment, an additional refrigerant evaporator comprising tubing mounted in said storage compartment, a readily detachable member covering said additional refrigerant evaporator, said detachable member comprising surface area portions corresponding to the shape of said tubing when said cover is in place which is formed of silver to provide a detachable member having a higher thermal conductivity than any of the exposed material in said storage compartment whereby frost accumulates thereon for removal from said refrigerator without interfering with the normal operation of said refrigerator.

References Cited in the file of this patent UNITED STATES PATENTS 2,370,267 Starr Feb. 27, 1948 2,442,978 Jones June 8, 1948 

